Jomehzadeh Ali, Shokrani Parvaneh, Mohammadi Mohammad, Amouheidari Alireza
Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Medical Physics, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Department of Medical Physics, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Adv Biomed Res. 2016 Nov 28;5:171. doi: 10.4103/2277-9175.194799. eCollection 2016.
The use of electronic portal imaging devices (EPIDs) is a method for the dosimetric verification of radiotherapy plans, both pretreatment and . The aim of this study is to test a 2D EPID-based dosimetry algorithm for dose verification of some plans inside a homogenous and anthropomorphic phantom and as well.
Dose distributions were reconstructed from EPID images using a 2D EPID dosimetry algorithm inside a homogenous slab phantom for a simple 10 × 10 cm box technique, 3D conformal (prostate, head-and-neck, and lung), and intensity-modulated radiation therapy (IMRT) prostate plans inside an anthropomorphic (Alderson) phantom and in the patients (one fraction ) for 3D conformal plans (prostate, head-and-neck and lung).
The planned and EPID dose difference at the isocenter, on an average, was 1.7% for pretreatment verification and less than 3% for all plans, except for head-and-neck, which was 3.6%. The mean γ values for a seven-field prostate IMRT plan delivered to the Alderson phantom varied from 0.28 to 0.65. For 3D conformal plans applied for the Alderson phantom, all γ1% values were within the tolerance level for all plans and in both anteroposterior and posteroanterior (AP-PA) beams.
The 2D EPID-based dosimetry algorithm provides an accurate method to verify the dose of a simple 10 × 10 cm field, in two dimensions, inside a homogenous slab phantom and an IMRT prostate plan, as well as in 3D conformal plans (prostate, head-and-neck, and lung plans) applied using an anthropomorphic phantom and . However, further investigation to improve the 2D EPID dosimetry algorithm for a head-and-neck case, is necessary.
使用电子射野影像装置（EPID）是一种用于放射治疗计划剂量验证的方法，包括治疗前和治疗中的验证。本研究的目的是测试一种基于二维EPID的剂量测定算法，用于在均匀和人体模型内对某些计划进行剂量验证。
使用二维EPID剂量测定算法从EPID图像重建剂量分布，该算法应用于均匀平板模型内的简单10×10 cm方形野技术、三维适形（前列腺、头颈部和肺部）以及人体模型（Alderson模型）内的调强放射治疗（IMRT）前列腺计划，以及患者体内的三维适形计划（前列腺、头颈部和肺部计划）（单次分割）。
在等中心处，计划剂量与EPID剂量的平均差异在治疗前验证时为1.7%，对于所有计划（除头颈部为3.6%外）均小于3%。在Alderson模型中实施的七野前列腺IMRT计划的平均γ值在0.28至0.65之间。对于应用于Alderson模型的三维适形计划，所有γ1%值在所有计划以及前后（AP-PA）射束中均在容差范围内。
基于二维EPID的剂量测定算法提供了一种准确的方法，可在均匀平板模型内二维验证简单10×10 cm射野的剂量、IMRT前列腺计划以及使用人体模型实施的三维适形计划（前列腺、头颈部和肺部计划）。然而，对于头颈部病例，有必要进一步研究以改进二维EPID剂量测定算法。
